You cannot assume a request is coming from a browser.
curl --referer http://www.example.come http://www.example.com
curl --referer http://www.example.come http://www.example.com
Atwood's point is that checking the "referer" will both be unreliable and, more importantly, lead to false positives; there are better alternatives, namely, double submitting cookies as I have pointed out elsewhere with regard to this article.